The present invention pertains generally to a water level monitors for toilet flush tanks. It is directed specifically to a self cleaning water level sensor and a flexible mounting system for adjusting the position of the monitor in the flush toilet.
Conventional toilets used in apartments and hotel rooms comprise a water flush tank and a bowl. Water is stored in the flush tank. The flush tank has an aperture in its base. A pipe connects the aperture to the bowl. The aperture is normally sealed by a ball valve or a flap valve. Water is admitted to the tank through an inlet valve. The inlet valve is controlled by an arm which is attached to the inlet valve at one end, and to a float member at the other end. To flush the toilet the ball valve is lifted allowing water to flow rapidly through the pipe into the bowl. When the tank is empty the ball valve falls back into position and reseals the aperture. When the tank is empty the level of the float which operates the inlet valve is lowered. The lowering of the float opens the water inlet valve and the tank begins to refill. When the float reaches the original level the water inlet valve is closed and the flushing cycle is thus complete. About 5 gallons of water may be used to flush a toilet bowl.
A common malfunction of the conventional flush toilet system occurs when the ball valve does not correctly reseat after the toilet is flushed. Water may thus drain continuously from the tank as quickly as it is admitted through the water inlet valve and the tank can not refill to the original level. The float attached to the inlet valve can also not return to its original position. The inlet valve may thus remain open and water may continue to flow until the malfunction is corrected. The malfunction may not be detected for several minutes, or even for several hours.
The refill time for a normally functioning flush system may be about two minutes. If a malfunction were not detected for an hour the water flow would be the equivalent of thirty toilet flushes which may be more than would occur in a household in one day.
Since the invention of the flush toilet mechanism the design of toilets has progressed to the point where they are aesthetically more pleasing as well as more efficient in operation. Modern ceramics have replaced the original iron tanks. Toilet bowls have been designed which may be effectively flushed with less water. The basic flushing mechanism however is essentially the same. Furthermore, the components of the flushing mechanism have been made lighter and less substantial, generally in the interest of cost reduction. Thus, despite the overall design, progress the incidence of malfunctions of the flush system have not decreased and may even have increased.
Several monitor systems for toilet flush systems have been proposed. The purpose of the systems is to produce an audible or visible indication of a flush system malfunction. U.S. Pat. No. 3,365,710, granted to M.C. Duplessey, describes a system based on a mercury switch attached to the actuating arm of a water inlet valve mechanism. The system relies on an electrical delay circuit to determine if the arm is operating consistent with the proper refill rate for the flushing tank. U.S. Pat. No. 4,011,553, granted to D. Barri, describes a system which relies on electrodes submerged in the water in the toilet flush tank. An upper set of electrodes detects the full level of the tank and a lower set of electrodes detects the lowest level of water in the tank.
U.S. Pat. No. 3,984,877, granted to Kirby, describes a monitor system based on a fluid delay circuit. A control tube is inserted, substantially vertically, in the flush tank. The control tube has apertures in the upper portion which allows the water in the flush tank to flood the control tube. Thus, when the flush tank is full, the water level in the tube is the same as the water level in the flush tank. The control tube also has a relatively small aperture in its base. When the flush tank is emptied at the beginning of the flush cycle water drains from the tank faster than it drains from the control tube through the aperture in the base. A float in the control tube is equipped with an electrical contact. The float and thus the electrical contact fall toward an another electrical contact as the water level in the control tube falls during a flush cycle. If the ball valve in the flush tank seals normally after the flush, the water level in the tank rises and prevents further fall of the float. If the flush tank does not refill, the float continues to fall. The electrical contact attached to the float then electrically connects a pair of contacts attached to the control tube. The connecting of the contacts closes a circuit which in turn creates an electrical signal which may be used to activate an alarm. The alarm may be audible, such as a buzzer, or may be a visible alarm such as a flashing signal light.
All of the above described monitor systems are apparently simple and effective. None of the systems, however, has found widespread commercial use. A possible reason is that while the systems are sound in principle, they are still, as far as the potential domestic user is concerned, relatively complicated to install and calibrate. Furthermore, for such systems to be useful, they must be reliable. The conditions inside a toilet flush tank however are not conducive to reliable operation. Mineral deposits may quickly build up on objects immersed in the flush tank. The slightly acid nature of untreated water from the typical domestic supply may corrode metal objects immersed in it.
To be acceptable for domestic use a water monitor device should be inexpensive. It should be easily installed, preferably without the use of tools. It should be simple to adjust, and above all, once installed and adjusted, it should function reliably, requiring no further adjustment or maintenance.
Of the above referenced systems the Kirby system comes closest to meeting the requirements of a commercially-acceptable system. Kirby, however, identifies a problem of mineral deposits in the drainage aperture of the control tube. Kirby teaches a method of compensating for mineral deposit build-up by using an adjustable aperture in the base of the control tube. The adjustable aperture may be enlarged to compensate for accumulation of mineral deposits therein. However, frequent adjustment may be necessary in areas in which the domestic water supply is hard or corrosive. The Kirby system also has a rigid mount for attaching the system to the toilet flush tank. The mounting system described would thus be difficult to adapt to the wide variety of modern flush tank shapes. The requirement for a variety of mounts to accommodate a variety of flush tank designs may increase the production costs for such monitoring apparatus.
Accordingly, it is an object of the present invention to provide a flush tank monitor system which is reliable and does not require frequent maintenance and adjustment.
It is another object of the present invention to provide a flush tank monitor system adaptable to a wide variety of flush tank designs.
It is a further object of the present invention to provide a flush tank monitor system which is easy to install.